IT DIDN'T EXACTLY make Page One of anybody's vacation scrapbook for '87, but more than a few homebound holiday motorists still have less-than-fond memories of their marathon crawl back from the beaches on Memorial Day weekend. It was the worst traffic mess anyone could remember, which prompted some less-than-charitable comments from us about Maryland Gov. William Donald Schaefer's much-ballyhooed "Reach the Beach" program. What most people reached quickly was their boiling point, often in tandem with that of their automobile radiators. From the appearance of things at the time, Mr. Schaefer's beach promotion looked a certified gubernatorial dud.

But unlike the traffic, the governor's program didn't stop there. Little by little over the summer, improvements were made that actually did turn things around -- or, more accurate, sent them forward. Transportation officials as well as veteran beachtrippers report that the going was better this year -- though hardly a guaranteed picnic at peak times. On many occasions, according to the traffic experts, the flow surpassed even the best estimated capacities -- thanks to changes brought about by the state.

Flashing signs, a telephone hot line, more police patrols and special radio stations helped to coach motorists through the trails, as well as to talk many people into traveling at off-peak times. Improvements on the bay bridge lanes, widenings of Rte. 50, express lanes and a reduction in the openings of the Kent Narrows drawbridge also made differences.

There will be more in years to come, according to the governor's aides, including additional widenings, bridge work and a new high road arc over Kent Narrows. Nobody yet is promising nonstop trips to the shore on Friday evenings or any pique-free peak times on holiday weekends. But Gov. Schaefer's continued attention and response may well produce still more stunning results.